Printers have become a major component of any modern business or home office. Indeed, printers have become an invaluable peripheral to any computing system. They are not without their problems however. Most printers today use a type of ink that contains some level of water or other liquid which is absorbed into the print media during the printing process. When this occurs, the media may expand in random locations to varying degrees depending on the amount of ink and type of media used. This absorption creates ripples, wrinkles, or what is known in that art as cockles in the media. Cockling may not only lead to an inferior final printed product, but may also lead to damage to the printer or media. Specifically, if the cockling is significant enough it may lead to the printer's carriage smearing ink on the media or even to the carriage crashing or jamming. These problems are often referred to as carriage smearing or carriage crashing respectively.
Additionally, cockling may occur when media types other than paper are used such as plastic-based medium. In order to better dry the ink which has been deposited on the plastic media, a heat or drying source such as a heat lamp or drying lamp is often used. However, the heat from the drying lamp may cockle the plastic media and thereby again alter the appearance of the final printed product as described above.
To an extent, the cockling of media has been controlled by a vacuum system which comprises a vacuum source coupled to a number of holes in the platen. A negative pressure is then created between the platen and the media being fed into the printer. The use of this vacuum system may better hold the paper to the platen so that it won't wrinkle. However, the level of vacuum pressure used may create its own problems. Specifically, if the vacuum pressure is too low, the media may cockle which, as mentioned above, may lead to carriage smears or crashes. If the vacuum pressure is too high, the printer may not be able to effectively advance the media being printed and the media being used may skew; both of which may cause horizontal banding in the image being printed.
Still further, adjustment of the vacuum level of the vacuum system in order to compensate for any cockling may prove to be difficult, especially if adjusted by an end user. This is because the required vacuum level for any one type of media used is dependent on the rigidity or stiffness of the media. Because it is difficult for the end user to measure stiffness of any one type of media, adjustment of the vacuum level so as to accommodate that type of media has proven to be even more difficult.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.